when I was in school we were taught that the human brain was really two brains - the left and right hemispheres. it seemed to explain how you could learn a skateboard trick in your normal stance, then have to learn it again switch.

no it isnt. it is derived from disparate progenitor cells.

"Two parallel neural ectoderm progenitors contribute to the developing brain"

https://www.nature.com/articles/s41593-026-02433-7

these are not separate organs these are separate "stem cell" populations.

under such a statement as submitted all of our organs that derive from varied populations of expressive constituency, would be amalgams of more than one organ.